Steps to reproduce:

Create a new 3D URP project
Go to Edit > Project Settings > UI Toolkit and enable "Advanced Text Generator" (enabled automatically on newer versions)
Import the attached "CalibriBold.ttf" font and "AtgShutdownCrash.cs" script into the project
In the Hierarchy, right-click and create UI Document
Attach the "AtgShutdownCrash.cs" script on the same GameObject
Reference the attached font in the Font property
Enter Play mode (text should appear in Game view)
Exit Play mode
Close the Unity Editor

Actual results: Closing the Unity Editor crashes (the bug reporter opens) instead of shutting down normally

Expected results: The Unity Editor closes cleanly without crashing

Reproducible with versions: 6000.3.0a5, 6000.3.18f1, 6000.4.12f1, 6000.5.0f1, 6000.6.0a7

Not reproducible with versions: 6000.3.0a4

Tested on (OS): Windows 11

First few lines of stacktrace:

0x00007FF81A2C2247 (Unity) UNITY_FT_Done_Face
0x00007FF81A378189 (Unity) _hb_face_for_data_closure_destroy
0x00007FF81A3E25D7 (Unity) hb_face_destroy
0xe394|0x00007FF81A3E2720 (Unity) hb_font_destroy
0xe394|0x00007FF81A22DB45 (Unity) FontAsset::ClearLookups

Notes:

Does not reproduce with the Standard generator, with asset-based/default fonts, or if the font is never rendered
All three conditions are required: a runtime-created dynamic FontAsset (FontAsset.CreateFontAsset), the text actually rendered, via the Advanced Text Generator. Removing any one prevents the crash
No actual corruption of the project seems to be present, except for it opening up the "recovery" popup when reopening project